Supercomputers and other large computer systems typically include a large number of computer cabinets arranged in close proximity to each other. FIG. 1, for example, illustrates a portion of a prior art supercomputer system 100 having plurality of computer cabinets 110 arranged in a bank. The computer cabinets 110 are arranged in a bank to conserve floor space and increase computational speed by reducing cable lengths between cabinets. Each of the computer cabinets 110 includes a plurality of computer module compartments 118 (identified individually as a first module compartment 118a, a second module compartment 118b, and a third module compartment 118c). Each module compartment 118 holds a plurality of computer modules 112. Like the computer cabinets 110, the computer modules 112 are also positioned in close proximity to each other to conserve space and increase computational speed. Each of the computer modules 112 can include a motherboard electrically connecting a plurality of processors, memory modules, routers, and other microelectronic devices together for data and/or power transmission.
Many of the electronic devices typically found in supercomputers, such as fast processing devices, generate considerable heat during operation. This heat can damage the device and/or degrade performance if not dissipated during operation. Consequently, supercomputers typically include both active and passive cooling systems to maintain device temperatures at acceptable levels.
To dissipate heat generated by the computer modules 112, the prior art supercomputer system 100 further includes a plurality of centrifugal fans 120 mounted to upper portions of corresponding computer cabinets 110. In operation, each of the centrifugal fans 120 draws cooling air into the corresponding computer cabinet 110 through a front inlet 114 and/or a back inlet 115 positioned toward a bottom portion of the computer cabinet 110. The cooling air flows upwardly through the computer cabinet 110, past the computer modules 112, and into a central inlet 122 of the fan 120. The centrifugal fan 120 then exhausts the cooling air outward in a radial pattern through a circumferential outlet 124.
One problem associated with the prior art supercomputer system 100 is the inability of the centrifugal fan 120 to move a sufficient amount of air through the computer cabinet 110 for adequate cooling when the density of the computer modules 112 increases. As more computer modules 112 are installed in a given space (e.g., by decreasing the spacing between two adjacent computer modules 112), available flow paths for cooling air decrease, thereby increasing the pressure drop as the cooling air flows past the computer modules 112. The centrifugal fan 120 typically has a generally flat operating curve (i.e., the generated pressure differentials are nearly constant with respect to different volumetric flow rates). As a result, as the centrifugal fan 120 increases the output pressure differential to compensate for the increased pressure drop, the flow rate of the cooling air through the computer cabinet 110 is significantly reduced. The reduction in cooling air flow can cause overheating of the computer modules 112, and thus adversely affect performance of the computer system 100.
Conventional techniques for increasing cooling air flow in densely packed computer cabinet 110 include increasing the size of the centrifugal fan 120 and increasing the operating speed of the centrifugal fan 120. There are a number of shortcomings associated with each of these solutions. First, increasing the size of the centrifugal fan 120 increases the power consumption of the centrifugal fan 120. In addition, the computer cabinet 110 may not have enough space to accommodate a fan 120 of increased size. Second, increasing the operating speed of the centrifugal fans 120 can cause a substantial increase in operating noise and power consumption.